Micropipetting apparatus

ABSTRACT

Apparatus for withdrawing minute quantities of a liquid medium into a liquid collecting apparatus. The so-obtained liquid medium is then transferred from the liquid collecting apparatus into a vessel containing another medium which interacts with the liquid medium collected to give information about the latter.

waited States Patent [191 Lefkovits et al.

[ Apr. 30, 1974 MICROPIPETTING APPARATUS [75] Inventors: Ivan Lefkovits,Bettingen; Otto Kamber, Basel, both of Switzerland [73] Assignee:Hoffmann-La Roche Inc., Nutley,

[22] Filed: Oct. 6, 1972 21 Appl. No; 295,646

52 U.S.Cl. 73/425.6 51 Im. Cl B01] 3/02 [58] FieldofSearch..222/263;73/425,4R,

[ 5 6 References Cited UNITED STATES PATENTS Guinn 73/4256 3/1969Wiggins ..73/425.6 3/1971 Lancaster 222/263 Primary ExaminerS. ClementSwisher Attorney, Agent, or Firm--Samuel L. Welt; Bernard S. Leon 5 7]ABSTRACT Apparatus for withdrawing minute quantities of a liquid mediuminto a liquid collecting apparatus. The soobtained liquid medium is thentransferred from the liquid collecting apparatus into a vesselcontaining another medium which interacts with the liquid mediumcollected to give information about the latter.

7 Claims, 3 Drawing Figures PATENTEBAPNOIBN 313071235 SHEET 2 UF 2 FIG.3

MICROPIPETTING APPARATUS DETAILED DESCRIPTION OF THE INVENTION Thepresent invention relates to a micropipetting apparatus. Moreparticularly, it relates to a micropipetting apparatus adapted tosimultaneously withdraw from a liquid containing vessel, very smallsamplings of a liquid, which samplings are substantially all of equalvolume and are of a very small magnitude, i.e., of the order of amicroliter.

Pipetting apparatuses which are capable of simultaneously withdrawing aplurality of samples of liquid to be pipetted are known. Such knownapparatuses, however, are generally suitable for withdrawing amounts ofliquid in excess of 25 microliters. In many instances, 25 microliters ismuch more than the amount needed and, thus, more liquid is withdrawnfrom the liquidcontaining medium than is needed for an intended purpose.Hence, waste of liquid and inefficiency result. I

The disadvantages in utilizing more liquid than is needed for study isparticularly apparent in such fields as, for example, research withtissue cultures. In this field, because of the high expenses incurred inobtaining the liquids, amounts in the order of magnitude of amicroliterare most preferably utilized for study.

With the general desire for miniaturization, there now exists the needfor a pipetting apparatus of simple construction and yet which issuitable for the simultaneouspipetting of a plurality of equal amountsof liquid in the order of magnitude of about a microliter.

This desideratum is achieved by the micropipetting apparatus provided bythe present invention which comprises a number of cannulas fastened to acarrier plate and a pump membrane fitted over the carrier plate, thepump membrane being in communication with a suction chamber by means ofa perforated plate provided with indentations which are disposed in sucha way that they each register with a cannula and determine the volume ofthe liquid which is to be pipetted.

The micropipetting apparatus provided by the present invention will nowbe described with reference to the accompanying drawings in which:

FIG. 1 is a sectional view of the cannula plate;

FIG. 2 is a sectional view of a part of a cannula plate;

FIG. 3 is a complete view of the micropipetting apparatus. v

The micropipetting apparatus comprises a cannula plate shown in FIG. 1made of stainless steel material which consists of a carrier plate 2having 60 cannulas 1 secured thereto. The cannulas are all of equaldimensions and are disposed on plate 2 in staggered relationship in sixrows, each containing 10 cannulas.

Over the carrier plate 2, there is situated a flat pump membrane 3 whichis made, for example, of rubber or of any suitable elastic syntheticmaterial. The membrane 3 is supported on a plate 4 having 60indentations 6. The transverse axis of each indentation 6 and thelongitudinal axis of each of the cannulas are disposed alongsubstantially the same line. In communication with each indentation isan opening 7. Opening 7 is disposed between pump membrane 3 and suctionchamber 5. The indentations 6 are all of the same volume, i.e., of theorder of magnitude of a microliter.

Fastening means is utilized to secure membrane 3 between plates 2 and 4and section chamber 5 to plates 2 and 4 as shown in FIG. 1. Any suitablesecuring means of the type shown in FIG. 3 may be utilized as thefastening means.

In order to withdraw samples, the suction chamber 5 is placed undervacuum in a conventional manner, whereby an adjacent portion of themembrane is sucked into each indentation 6. An aliquot of liquid, whichcorresponds to the volume of an indentation 6 is withdrawn from a liquidcontaining vessel into each cannula.

In order to deliver the liquid samples to a liquid receiving vessel, itis sufficient to place the suction chamduced in the membrane by thesuction.

FIG. 3 is a view of a preferred embodiment of the micropipettingapparatus provided by the present invention. The micropipettingapparatus shown in FIG. 3 can be operated as follows:

The microtitration plate 12, which has 6O recesses filled with culturemedia, is placed on a carrier plate 13. The cannulas 1 of the cannulaplate are then lowered until they are each immersed in the culturemedia. By means of a foot pedal 14, the suction chamber 5 is placedunder vacuum and 60 samplings are drawn into each of the respectivecannulas. The microtitration plate 12 is removed and an agar plate or aplate having another nutrient medium thereon, is placed under thecannula plate 10. The vacuum condition which have been imparted to thesuction chamber 5 is removed, whereby the liquid in the cannulas isdischarged under the influence of gravity onto an agar plate or thelike.

'We claim:

1. A micropipetting apparatus for pipetting a liquid comprising a liquidreceiving cannula secured to a carrier plate and extending downwardlyfrom the underside thereof, the upper end of said cannula extending tothe upperside of the carrier plate, a pump membrane disposed over theupperside of said carrier plate, a second plate provided with an openingoverlying the pump membrane, said opening being in registry with saidupper end of said cannula, said opening being provided by an indentationand a bore in a second plate in axial alignment and in communicationwith each other, said indentation extending from the surface of the sideof said second plate overlying the pump membrane to a point between thelast mentioned surface and the surface of the upperside of the secondplate, said bore extending from the surface of the upper. side of saidsecond plate to said point, the diameter of the portion of the bore atthe surface of the upper side of the second plate being less than thediameter of the portion of the indentation at the surface of the side ofthe second plate overlying the pump membrane, means for moving the pumpmembrane so that a portion thereof is drawn into said indentation in thesecond plate whereby withdrawal of a predetermined amount of said liquidinto said cannula occurs.

2. .A micropipetting apparatus as defined in claim I which comprises aplurality of cannulas and openings whereby a plurality of substantiallyequal amounts of said liquid is withdrawn from said vessel containingsaid liquid.

3. A micropipetting apparatus as defined in claim 2 wherein the meansfor moving the pump membrane is provided by a suction chamber overlyingthe pump membrane.

4. A micropipetting apparatus as defined in claim 3 wherein theplurality of cannulas are disposed in a staggered relationship.

5. A micropipetting apparatus for pipetting a liquid comprising a liquidreceiving cannula secured to a carrier plate and extending downwardlyfrom the underside thereof, the upper end of said cannula extending tothe upperside of the carrier plate, a pump membrane disposed over theupperside of said carrier plate, a second plate provided with an openingoverlying the pump membrane, said opening being in registry with saidupper end of said cannula, means for moving the pump membrane so that aportion thereof is drawn into said opening in the second plate wherebywithdrawal of a predetermined amount of said liquid from a vesselcontaining said liquid into said cannula occurs and wherein the openingin the second plate comprise a large opening in the side of the plateadjacent the pump membrane and a smaller opening extending therefrom,the upper end of said smaller opening being in communication with asuction chamber.

6. A micropipetting apparatus as defined in claim 5 wherein themagnitude of the liquid drawn into the cannula is of the order of amicroliter.

7. A micropipetting apparatus as defined in claim 5 wherein themagnitude of the liquid drawn into the cannula is of the order of amicroliter.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE 0F CORRECTIONPATENT NO. 3,807,235 1 DATED April 30, 1974 INVENTOMS) IVAN LEFKOVITSAND OTTO KAMBER It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below: I r

Cover page, after "[21] Appl. No.: 295,646" insert:

[30] Foreign Application Priority Data e October 13, 1971 SwitzerlandNo. 14,907/71 Signed and Sealed this O twenty-second Day Of Jane 1976[SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ommissirmer of Patents and Trademarks

1. A micropipetting apparatus for pipetting a liquid comprising a liquidreceiving cannula secured to a carrier plate and extending downwardlyfrom the underside thereof, the upper end of said cannula extending tothe upperside of the carrier plate, a pump membrane disposed over theupperside of said carrier plate, a second plate provided with an openingoverlying the pump membrane, said opening being in registry with saidupper end of said cannula, said opening being provided by an indentationand a bore in a second plate in axial alignment and in communicationwith each other, said indentation extending from the surface of the sideof said second plate overlying the pump membrane to a point between thelast mentioned surface and the surface of the upperside of the secondplate, said bore extending from the surface of the upper side of saidsecond plate to said point, the diameter of the portion of the bore atthe surface of the upper side of the second plate being less than thediameter of the portion of the indentation at the surface of the side ofthe second plate overlying the pump membrane, means for moving the pumpmembrane so that a portion thereof is drawn into said indentation in thesecond plate whereby withdrawal of a predetermined amount of said liquidinto said cannula occurs.
 2. A micropipetting apparatus as defined inclaim 1 which comprises a plurality of cannulas and openings whereby aplurality of substantially equal amounts of said liquid is withdrawnfrom said vessel containing said liquid.
 3. A micropipetting apparatusas defined in claim 2 wherein the means for moving the pump membrane isprovided by a suction chamber overlying the pump membrane.
 4. Amicropipetting apparatus as defined in claim 3 wherein the plurality ofcannulas are disposed in a staggered relationship.
 5. A micropipettingapparatus for pipetting a liquid comprising a liquid receiving cannulasecured to a carrier plate and extending downwardly from the undersidethereof, the upper end of said cannula extending to the upperside of thecarrier plate, a pump membrane Disposed over the upperside of saidcarrier plate, a second plate provided with an opening overlying thepump membrane, said opening being in registry with said upper end ofsaid cannula, means for moving the pump membrane so that a portionthereof is drawn into said opening in the second plate wherebywithdrawal of a predetermined amount of said liquid from a vesselcontaining said liquid into said cannula occurs and wherein the openingin the second plate comprise a large opening in the side of the plateadjacent the pump membrane and a smaller opening extending therefrom,the upper end of said smaller opening being in communication with asuction chamber.
 6. A micropipetting apparatus as defined in claim 5wherein the magnitude of the liquid drawn into the cannula is of theorder of a microliter.
 7. A micropipetting apparatus as defined in claim5 wherein the magnitude of the liquid drawn into the cannula is of theorder of a microliter.